***If only people had to walk everywhere and carry all of there burdens themselves, the world would be such a better place. ***
The Mayan Indians also invented the wheel and used it only for kid’s toys. I guess they felt, as my old boss used to say, “Walking ain’t out of Style!”
https://uncoveredhistory.com/mesoamerica/wheeled-toys/
Actually, inventing the wheel was easy and many civilizations invented it but never made use of it.
The hard part is the axle. A wheel without an axle is useless. A proper axle transfers the load to the wheel while permitting the wheel to turn. It also must permit the wheel to turn with little friction. And add the major complication of front and rear wheel alignment if you go from a two to four-wheel cart.
A toy axle and wheel can do these things with little trouble because the load and friction are tiny and their time in use are negligible.